The present invention relates to ultrasound systems and, more particularly, to an ultrasound system for continuous imaging of an organ inside a patient""s body and for controlling release of an encapsulated agent from a carrier.
Ultrasound technology is widely used for imaging various organs in a patient""s body and for diagnosis of tissue pathology. Commonly, ultrasound examinations are performed by placing a probe containing an ultrasound transducer on the surface of the patient""s body. This is done to make a specific diagnosis and not for prolonged monitoring of the patient.
U.S. Pat. No. 5,598,845 to Chandraratna et al. (hereinafter xe2x80x9cthe ""845 patentxe2x80x9d), entitled Ultrasound Transducer Device For Continuous Imaging Of The Heart And Other Body Parts, which is incorporated herein by reference, describes an ultrasound transducer device that can be used for continuous imaging of a patient""s heart or other body organs for diagnosis or monitoring. An ultrasound transducer is mounted in an enclosure that is secured to a holding pad, and the holding pad is attached to a surface of a patient""s body. The significant features of two embodiments of such a device are illustrated in FIGS. 1 through 6, below.
FIG. 1 shows a view of an ultrasound transducer device 1 for continuous imaging as envisioned in the ""845 patent. Transducer device 1 is adhered to the chest wall, between the ribs 23 of a patient. A conductor 2 is shown coming out of the top cover 10 of transducer device 1. Conductor 2 couples an ultrasound-activating signal from an ultrasound processor 50 to a transducer that is located within device 1 and positioned adjacent to the patient""s body. Conductor 2 also couples, to ultrasound processor 50, an ultrasound echo signal reflected from tissue within the patient""s body. The ultrasound echo signal is processed by ultrasound processor 50 to produce an image on display 60.
FIGS. 2 and 3 are, respectively, a perspective view of one embodiment of transducer device 1 and a partial, cross-section view of transducer device 1 mounted on a patient""s body, taken along line 3xe2x80x943 of FIG. 2. Transducer device 1 comprises a hollow enclosure 6 with an ultrasound transducer 16 mounted inside the bottom of enclosure 6. Conductor 2 is connected to transducer 16 and exits the assembly through a hole in the top cover 10. A holding pad 4 has a hole (not shown) in its center, a collar 8 attached to its top side around the hole and an adhesive layer 5 affixed to its underside. Enclosure 6 is held within collar 8. The top cover 10 includes a projecting stub 12, which is used for manually adjusting and rotating the transducer assembly in relation to holding pad 4. In use, transducer device 1 is adhered to the skin surface 21 of a patient.
FIG. 4 shows an embodiment of a transducer device la that permits remote orientation adjustment. FIGS. 5 and 6 show partial cross sectional views taken along line 5xe2x80x945 of FIG. 4. Transducer device 1a is identical to transducer device 1 except for the addition of an adjusting assembly. All other parts of transducer device la are the same as those described for transducer device 1 and are identified in FIGS. 4, 5 and 6 with the same numerals as are used in FIGS. 2 and 3.
The adjusting assembly comprises an actuator support structure 22 and three actuating pins 24. FIG. 6 shows the result of an operator pushing down on one or two of the actuating pins 24. This action causes the enclosure 6 to swivel with one side downwards, placing the face of the transducer 16 at an angle to the patient""s skin surface 21 and thereby adjusting the area scanned by transducer 16. Actuator pins 24 can be moved either manually or by a small remotely controlled mechanism (not shown) mounted on top of support structure 22. Such a remote controlled mechanism facilitates remote adjustment of the scanning area.
For many applications in medical ultrasound, especially vascular and cardiac applications, it is often desirable to selectively image tissues or blood. Contrast agents such as encapsulated air bubbles have been shown in the prior art to improve the visibility of these selected tissues. Additionally, such contrast agents have proven useful in the localized delivery of drugs.
U.S. Pat. No. 5,190,766 to Ishihara, entitled Method Of Controlling Drug Release By Resonant Sound wave, which is incorporated herein by reference, describes a method of using ultrasound for controlling the release of a drug from a drug carrier. The drug carrier is typically a suspension containing microcapsules. The fundamental principle behind this method is that when the drug carrier is insonified with a sound wave having a frequency corresponding to the resonance frequency of the drug carrier, the sound energy is absorbed and ruptures the microcapsules, allowing release of the drug. The drug can thus be selectively administered to a local region of a patient""s body. Such isonification is performed using a standard transducer on a dosage by dosage basis. In other words, for each dose of the drug a separate ultrasound session has to be scheduled.
The present Inventor has recognized a need for an ultrasound system that provides continuous imaging of a patient in conjunction with the release of an agent from a carrier. Furthermore, such a system should measure a physiological parameter of the patient and automatically dispense the carrier into the patient""s body on a continuous basis. Additionally, some form of monitoring should be performed to evaluate the effectiveness of the system.
The present Inventor has discovered that the ultrasound unit, described in the ""845 patent, can be advantageously used in a system which continuously controls the release of a drug from a drug carrier that has been introduced into the patient""s body. Further, such a system can continuously and automatically provide a localized delivery of agent, thereby substantially enhancing the usefulness of the system described in the ""766 patent.
The present invention is an ultrasound system and method that enables release of an encapsulated agent from a carrier. The encapsulated agent can be a therapeutic agent, i.e., a drug, or it can be a contrast agent for improving the quality of an ultrasound image.
An ultrasound transducer is adhered to a patient""s body over an organ of interest, and then adjusted for optimal ultrasound imaging. Once the transducer has been adjusted, it is locked into place so as to fix the imaging plane. An imaging technician is thus not required to maintain the desired plane. An ultrasound exposure can then continue unabated according to a predefined schedule. The ultrasound system can be programmed to produce emissions based on varying parameters such as drug type, carrier type, organ of interest, disease state, and patient state and condition.
In the preferred embodiment, the ultrasound system measures a physiological parameter of the patient to evaluate the patient""s response to an agent. Thereafter, the system determines whether the dosage of the agent should be increased or decreased, and if so, it adjusts the quantity of the agent delivered by an injection, intravenous carrier, or other transport means.
The present invention offers several improvements over the prior art. The present invention allows for continuous drug delivery and response monitoring of a patient over a period of time without requiring the presence of a dedicated ultrasound technician. Advantageously, the invention can store sequential images over a period of time for subsequent review and trend analysis. It also enables medical personnel to visualize a region of interest in a patient, pre-drug, peri-drug, and post-drug release. In addition, it tracks the amounts of encapsulated agent and carrier delivered to the patient over time.